The present invention relates to a process to manufacture pressed products from non-caking salt, the resulting products, and their use.
Pressed products of salt are well-known. Examples of such products are salt licks and smaller bricks or tablets of salt for use in water softening installations. Typically, such pressed products are formed from salt that does not contain an anti-caking additive.
However, when salt that does not contain an anti-caking additive is used, salt will cake during storage and, accordingly, requires special measures such as immediate pressing after production. In practice, this means that pressing can only take place at the salt production facility, which is undesired. The use of common anti-caking additives in the salt prevents caking from occurring when the salt is stored, but will interfere with the process of (com)pressing the salt into a certain shape. Furthermore, if salt comprising sodium or potassium ferro cyanide, the most commonly used anti-caking additives, is used, the shape of the pressed products is easily disturbed, especially if they are submerged in brine. This means that smaller salt crystals will be dispersed in the brine, a phenomenon also known as xe2x80x9cmushingxe2x80x9d, which can result in plugging of filters, feed lines, etcetera, which is undesired.
Surprisingly, we have found that the use of salt comprising one or more specific anti-caking agents does not lead to caking under normal conditions, e.g., in silos and 1,000 kg big bags, which are also known as flexible intermediate bulk containers (FIBC). However, the same non-caking salt can be formed into (com)pressed products, such as licks, bricks, and tablets, that retain their shape even when submerged in brine for a period of at least three weeks, preferably six weeks, and that show low levels of mushing. An explanation of this phenomenon, i.e. that this anti-caking agent prevents caking at lower pressures (during transport and storage), but allows caking/shaping when high pressures are applied, has not been found as yet.
The present invention generally relates to the use of salt comprising one or more iron ammonium hydroxypolycarboxylic acid complexes, preferably iron ammonium citrate complexes, as an anti-caking additive, for the manufacture of pressed products, the formed pressed products, and the use of said pressed products.